The present invention relates to a color image forming apparatus which forms color toner images on a belt type image forming unit by the electrophotographic method and transfers the toner images onto a transfer paper to obtain images.
There are various types of color image forming apparatus available. Generally, a belt type image forming apparatus comprises a photosensitive belt stretched between two rollers, and a plurality of developing units containing different color toners mounted along the lower side thereof, by which latent images are formed on the photosensitive belt in accordance with the number of decomposed colors of the original image and developed by the group of developing units while the photosensitive belt is rotated a plurality of times so as to form color images. The color images are transferred onto a transfer paper fed from the paper feed cassette in the cassette storing chamber installed under the group of developing units so as to obtain color copies.
Such a photosensitive belt in a color image forming apparatus has an advantage in that space can be effectively used, because it can make a U-turn in a small curvature and have a flat surface, unlike a photosensitive drum. The photosensitive belt has another advantage in that by installing a separation electrode at the small curvature part, the transfer paper can be easily separated.
In the above color image forming apparatus, the group of developing units are mounted between the photosensitive belt and the cassette storing chamber, and the paper feed path and the paper feed means between the cassette storing chamber and the transfer part of the photosensitive belt are installed along the inner surface of one side wall of the apparatus body, passing round the outside of the group of developing units. The insertion port of the cassette storing chamber is located on the side wall of the apparatus body on the opposite side of installation of the paper feed path and the paper feed means so that paper feed cassettes can be inserted in the paper feed direction.
When such a method in which paper feed cassettes are inserted from the opposite side of the paper feed path and the paper feed means is used, both sides of the apparatus are required to open, when necessary, for removing jammed transfer papers, and a wide space is required for installation of the apparatus, causing problems for copying operation and maintenance.